Three projects will be pursued during the coming year. Further immunologic studies will be performed using a heterotopic lung allograft in abdomen. This preparation will permit the preparation of a larger number of recipient animals for study and the lung itself will be readily accessible. A series of migration inhibitor factor (MIF) tests and T- and B-cells quantitation in peripheral blood will be performed serially. Our usual immunosuppression regimen will be compared with an enhancement procedure. Second, the heart response to bilateral lung replants versus bilateral allotransplants will be followed and compared. Cardiac contractility indices, dp/dtmax,IIT, and the ratio dp/dtmax//IIT, will be monitored by an on-line computer system. Third, blood flow distribution patterns before and after replantation, and allotransplantation during rejection, will be studied by means of tagged microspheres using three different isotopes. By means of a computer technique flow distribution to the entire lung can be analyzed three times in each animal with the usual radionuclide-tagged microspheres. BIBLIOGRAPHIC REFERENCES: Kondo, Y., Turner, M.D., Cockrell, J.V., and Hardy, J.D.: Bilateral pulmonary allotransplantation: Technical improvements, pulmonary edema, rejection patterns and immunosuppression. Bull. Soc. Int. Chir., 34:31, 1975. Hardy, J.D.: Lung Transplantation, in Gibbon's Surgery of the Chest. W.B. Saunders, 1976.